
A PvE area, large, but not instanced only to your group. You can enter any time, ala PvE. The idea is it's very high level, monsters repawn and patrol randomly. Obviously you'd have to cap the number of teams entering before a new instance is created. I was thinking at least 6 teams of 4, as AB shows it's technically possible currently.
The trick is, to actually fight through the PvE monsters, your team needs to create a temporary alliance with other teams or your destroyed

Now obviously there are alot of details to work out, and potential exploits etc, but I think it could be done with the current tech, and would be alot of fun.
Some basic ideas to start with. No res shrines. The end section could be a stand you need to cap HoH style perhaps, which then opens a portal for your team to escape to a rewards area. Only single teams can enter the portal, not temp alliances. Perhaps stockades within the PvE area your team can hold for a respite. Maybe make them critical to survival, with large waves of monsters that you wont survive unless in a defensive position.
How the alliances are formed and dissolved will be the difficult part gameplay wise, to avoid exploits. I was thinking some sort of addition to the party window which adds the enemy party leader automatically, which they can accept or reject. Allied teams do not automatically target each other, but can be attacked, ala friendly beasts. An attack dissolves the alliance of course.
You should not be able to zone instances as in towns, and entry into the area is always random to close out more exploits.
I think this has alot of potential, so please add your ideas. It's sort of a combo of FoW, HoH and AB. You never know, ANET may listen
